Linux facade
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I believe that you must always hear this name, it is the most popular operating system, the operating system used by 30% of the server on INTERNTE, I will now talk about its development history, Have you And applications.
What is Linux? It is an open source network operating system, similar to UNIX, which can run on platforms such as X86 PC, Sun SPARC, Digital Alpha, 680x0, PowerPC, MIPS, etc., can say that Linux is the most operating system currently running hardware platform., But it is mainly for Intel PC hardware platforms. So it can be said: Linux is a complete implementation of UNIX on the PC. Strictly speaking, we said Linux is a kernel, and we generally use Linux distribution, namely a software package made from a Linux kernel and system tools, etc. This eliminates the user needs to be compiled under other operating systems, so that the user is convenient for the user, so that Linux installation is as convenient as Windows (as shown in Figure 1 is the installation interface of RedHat7.3).
There are currently most popular releases from:
Redhat Linux: Redhat Linux is one of the earliest commercial versions of Linux. It has achieved great success in the US and other English national markets. The latest version is Redhat Linux 7.3, which is based on the Linux 2.4.18-3 kernel.
SUSE Linux: SUSE is developed by the Germans and is one of the most popular versions in the European continent. The latest version is SUSE 8.0, based on the Linux 2.4 kernel.
Linux Mandrake: Linux Mandrake is a high quality business version. It is built in the early Red Hat release, its openness and scalability without Redhat distribution, but it has some commercial software.
TurboLinux: Turbolinux includes a series of applications, a desktop, documentation, and technical support for GUI (Xfree86 3.3), is one of the earliest Linux in China.
Red Flag Linux: Red Flag Linux desktop version 3.0 and red flag Linux server version and other system column products, raised the red banner of Chinese Linux.
Linux development process
Linux is a free operating system created by Linus Torvalds (such as Figure 2, Linux and his Linux) in 1991 Reading Helsinki University. Initially written a program in the assembly language to handle multi-task switching in 80386 protection mode, but this program cannot be counted as an operating system, and the real Linux operating system is from Minix. MINIX is developed by Professor Andrew Tannebaum, published on the Internet, and is used by students around the world. Minix has more UNIX features, but is incompletely compatible with UNIX. LINUX is ultimly minix, decided to design a more complete UNIX PC version for Minix users, issued Linux 0.11 version in 1991, but it only has a simple prototype with the operating system kernel, and cannot run well, and must be in Minix After compiling on the machine, you can run. At this time, Linus decided to separate, and wrote a system that can be independent of the hardware platform. On August 25, 1991, Linus Torvalds was freely spreading Linux on the Internet and issued the first open source of Linux, in 1991. On October 5, Linux 0.0.2 released, which can be running BASH (a software for users and operating system kernel communications) and GCC (GNU C compiler). This open source operating system quickly causing the attention of hackers and joined Linux's kernel programs through computer networks, making Linux more perfect. Since then, a spectacular open source movement in the history of software development is triggered. In the initial Linux requires all source code to be disclosed, it allows it as business behavior, but this pure free software is ideal for Linux's popularity and development, so that the release of Linux 0.02, Linux Officially accepted GPL and became the main member of the GNU camp. (GPL, universal public license agreement, is opposite to traditional business software license agreement, so it is called Copyleft.gpl to ensure that anyone has the freedom of sharing and modifying free software. Anyone has the right to obtain, modify and re-release The source code of the free software, and specifies that the source code of free software can be obtained without increasing additional costs. At the same time, the derivatives of free software must be used as the license agreement it re-issued. And the GNU project is to establish Freely released, portable UNIX operating systems.) Linux is developed in the Internet Open environment, which is constantly perfect by high level hackers around the world, and free for users. In the end of 1993, the end of 1993, Linux 1.0 is finally born! Linux 1.0 is already a fully functional operating system, and the kernel is compact and efficient, and the performance of the hardware can be given to the performance of the hardware. It can also be smooth on the 80386 machine of 4M memory. Running, 2.1.xx series kernel Linux To adapt to the rapid development of hardware, start the high-end road, almost 1.3 version, began to transplant to other hardware platforms, can already run in Dec Alpha, Sun SPARC, M68000, And on computers such as MIPS and PowerPC. Despite this, it still follows the commercial UNIX version of the POSIX standard, what is the POSIX standard? It is an independent UNIX standard (IEEE), which is called a portability operating system interface (PSOIX) of the computer environment. This standard defines how UNIX systems operates, and the system call has also been specifically discussed. PSOIX limits all UNIX versions must rely on mass standards. The existing general Unix and popular versions are followed by POSIX standards, while Linux follows the POSIX standard from the beginning. Linux features and technical advantages
1. Low price Linux is often propaganda to be free, and in fact, Linux is not a completely zero-cost solution and does not organize the organization in practical applications, using a software without technical support protocol.
The famous manufacturers and neighboring dealers who provide Linux technology support have now emerged. With a large number of paid third-party technical support, Linux will be accepted by more and more corporate users.
The organization is surprisingly discovered that Linux has a significant advantage in cost of licensing costs, especially for large number of users and large number of computer equipment.
For example, in the digital visual special effects of movie "Titani No.", Digital Domain needs a large number of servers to process the operational task. In the end, they installed 105 Compaq and Digital's Alpha server, and the operating system used Linux. Although approximately fundamental savings can not be disclosed, Digital Domain's website claims that the reason for use Linux is due to funding problems. (Of course, the performance of the Linux system is extremely outstanding. Otherwise, there is no significant difference. This standard is likely to run a UNIX program. UNIX has a rich application, and most operating systems today use the POSIX 1003.1 standard as achieving targets. Linux is no exception, it fully supports the POSIX 1003.1 standard. According to the Terms of GNU's Ordinary Public License Agreement, any entity has been modified to Linux without disclosing the corresponding modified source code, which limits the product that wants to use the Linux system to generate a private copyright. behavior.
3. Stability and safety people will often mention a problem why Linux is hardly collapsed, and Linux's stability is because it is not like other operating systems, and the vulnerability is endless. The inspection data shows that Linux has the same reliability as other UNIX systems and large operating systems such as VMS, IBM mainframes. The reason is not difficult to obtain, the stability of the system mainly depends on the structure of the system design. The structure of computer hardware has not made special changes since the 1981 design, and continuous backward compatibility makes the application software that makes the programming style barely transplanted to the latest version of Windows. This software development model is greatly obstructed. Development of system stability. Another system of easy-to-collapse, it lacks memory usage protection and lack of seizures of multitasking's shortcomings, amazing is the same as that of its friendly use interface, which is Macintosh although there is such a major defect but there is no one. Cancer is frequently crazy.
The stability of Linux is not an unexpected exception, and stability is the commonality of all large computer operating systems. WINDOWS and Apple are sometimes abnormal. The UNIX design system shared by Linux is a long-term practical test. Linux learned the experience of the development of the UNIX system in the nearly 1/4th century. The Linux operating system reflects the design concept of the first modern operating system and the most accomplished time test. Program. The most striking thing is the development mode of Linux development source code, ensuring that the vulnerability of any system can be found and corrected in time.
At the same time, IPChains implemented in the latest Linux 2.4, IPChains, IP Filter / Network Address Translation (NAT), is replaced by Netfilter. The motivation generated by Netfilter is the unreasonableness of the IPChains code structure. In fact, this structure is inherited from the IPFWADM of the 2.0 series kernel. To this end, Netfilter adopted a new mechanism. Compared to Ipchains, Netfilter is not a specific implementation of the package filtering, but a set of frame structures. Various package filters, the NAT function module can be built on the frame structure, thereby providing better flexibility and scalability. Linux application field
Business development:
In a commercial development system, executing CA / Clipper (the meaning of the object-oriented compiler based on DBASE and FOX superfines is that Clipper's developer can adapt to Linux operation only to the software. The result is the function. The same, and performance is improved, in the same hardware conditions, the speed is 20-200 times faster than the DOS version.
Network Server :
Linux can be configured to use NFS, Apple Talk, and NetBIOS protocols. Its sexual and low price is attractive. It is also a good purpose for Linux by LAN bridge. When Linux is running in a RISC and SMP (symmetrical multiprocess) hardware system, it can make a rigorous background processing convenience and ease of use.
2. Internet Server:
Internet server uses an important application for Linux. The Internet and intranet server based on Linux and Apache are low, performance excellent and easy to maintain. In the United States, most of the cheap servers are based on Linux. According to InfoBeads, 31% or more ISP is using Linux. Linux can be used as WWW servers, domain name servers, firewalls, FTP servers, mail servers, etc. All of these features can be provided with a single server. Linux is an excellent, standard web web application platform that uses it as a router, firewall, web server, email server, database server, and directory server to create a perfect, secure Internet site.
3. Database server
For commercial applications, those technologies are the most important? Telephone and network routing are obviously a key part of the commercial system, which will transfer important information from storage to the needs. The database is the brain of business operation. It may store all key business customers, as well as related business processing, and these may be your life. According to IDC's report, the LINUX database market will increase from $ 42 million in 2000 to $ 7.8 billion in 2005.
LINUX related certification and training
Linux has gradually received attention and use of the business community, and the relevant job opportunities and capacity requirements will be more and more, so no matter which industry, Linux workers must constantly learn from self-learning, training courses or participate in all types. Professional certification is enriching yourself, making yourself getting more careful. Internationally, the main certification pathway is mainly, one is the Red Hat's Certified Engineer (RHCE) Program hosted by Red Hat. The other is the LPI (Linux Professional Institute). There are a lot of domestic Linux, such as TurboLinux (TLCE) certification, Red Flag Linux Certified Engineer (RCE) certification. Exams and training are in China. If you want to stand out from thousands of MCSEs, CCNA competition, you will have to become a good Linux certified engineer, and our Linux certification is lower than other IT certified prices.
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